1. Field of the Invention
The present invention relates to an article conveying device which is used to convey a plurality of articles such as bags or containers at a high speed and more particularly to a conveying device in which articles supplied intermittently in a plurality of rows are discharged continuously in a single row or articles supplied continuously in a single row are discharged intermittently in a plurality of rows.
2. Prior Art
Japanese Patent Application Laid-Open (Kokai) No. H2-296617 (corresponding to U.S. Pat. No. 5,096,041) discloses a conveying device in which an endless conveyor on which numerous holders are disposed at equal intervals rotates in one direction along a ring-form track that has a pair of parallel sections and in which the operating characteristics differ between first side of the parallel sections and the second side of the parallel sections. In one set of operating characteristics, the endless conveyor moves intermittently on the first side and runs continuously on the second side. As a result of these operating characteristics, a plurality of holders can be simultaneously supplied with articles on the first side of the conveying device, and these articles can be continuously discharged on the second side of the conveying device.
The above-described prior art discloses in a concrete manner a mechanism for obtaining different operating characteristics on the different sides of the respective parallel sections of an endless conveyor. This mechanism is equipped with a pair of rolls which are rotably held on a carriage, an endless conveyor which is mounted on these rolls, a driving wheel which rotationally derives the endless conveyor, and a cam which is mounted on a common drive shaft with the driving wheel and rotates together with the riving wheel so that the carriage performs a reciprocating movement.
Furthermore, in Japanese Patent Application Laid-Open (Kokai) No. H10310230, a conveying device is described. In this conveying device, an endless chain on which numerous holders are disposed at equal intervals is mounted on a pair of sprockets so that the endless chain is rotated in one direction along a ring-form track which has a pair of parallel sections. The endless chain intermittently stops on a first side the parallel sections and runs continuously on a second side of the parallel section.
The above-described prior art disclosed in a concrete manner a mechanism for obtaining different operating characteristics on the different sides of the respective parallel sections. This mechanism which is equipped with: a separate pair of sprockets installed coaxially in positions beneath the pair of sprockets, an endless chain used for driving which is mounted on this separate pair of sprockets, a connecting member which holds the pair of sprockets so that the sprockets are rotatable, and intermittent-driving and continuous-driving sprockets which are respectively disposed on the first and second sides of the parallel sections of the endless chain used for driving.
In the conveying devices described above, a single row or a plurality of rows of articles supplied intermittently on the first side of the parallel sections can be continuously discharged in a single row on the second side of the parallel section. However, in the case of the mechanism described in Japanese Patent Application Laid Open (Kokai) No. H2-296617, the reciprocating movement of the carriage is accomplished by a cam, and the cam and driving wheel are simultaneously rotated by a single drive shaft. As a result, the system can only be operated in a pattern determined at the time of the initial setting of the stroke of the carriage and the number of article supplied at one time, etc. Thus, the system lacks all-purpose adaptability.
On the other hand, in the case of the mechanism described in Japanese Patent Application Laid-Open (Kokai) No. H10-310230, the mechanism has a structure in which all of the loads involved in the realization of the above-described operating characteristics (the sprockets that perform a reciprocating movement, the numerous holders that change their running speed, etc.) are applied to a single endless chain used for driving. As a result, an unreasonable amount of force is applied to the endless chain used for driving, so that this chain tends to stretch. Consequently, the positioning precision drops during operation (i.e., the stopping positions of the holders shift). Especially in the case of a high-speed operation, the acceleration of the sprockets and holders is great, so that the load applied to the chain is also increased. Moreover, in the conveying device described in Japanese Patent Application Laid-Open (Kokai) No. H10-310230, the articles are supplied in a single row; however, the positioning precision is even more important in cases where numerous articles are simultaneously supplied in a plurality of rows.
Accordingly, the present invention is made in light of the problems in the prior art.
The object of the present invention is to provide an article conveying device in which articles supplied intermittently in a plurality of rows are discharged continuously in a single row, or articles supplied continuously in a single row are discharged intermittently in a plurality of rows, and the article conveying device has all-purpose adaptability which allows the selection of various patterns of operating characteristics, etc., and the positioning precision of the conveying device is prevented from dropping even in the case of a high-speed operation.
The article conveying device of the present invention is provided with: a rotational conveying mechanism which rotationally conveys numerous article holding members disposed at equal intervals in one direction along a ring-form track (or a race-track shape path) that has a pair of parallel sections, and a reciprocating driving mechanism which causes the rotational conveying mechanism as a whole to perform a reciprocating movement for a specified distance along the parallel sections; and the rotational conveying mechanism and reciprocating driving mechanism have their own driving sources. In addition, the article holding members have a moving speed that is synthesized from the rotational conveyance and reciprocating movement, and the article holding members are moved intermittently a specified distance (which is a specified distance that is an integral multiple of the attachment spacing of the article holding members) on the first side of the parallel sections and are moved continuously at a constant speed on the second side of the parallel sections.
In this conveying device, it is desirable that the driving sources of the rotational conveying mechanism and reciprocating driving mechanism both be servo motors. Furthermore, in order to realize the above-described operating characteristics, the rotational conveying speed of the article holding members is set at different values during the advancing movement and return movement of the rotational conveying mechanism, and the speed of the advancing movement and the speed of the return movement of the rotational conveying mechanism are set at different values.
In the conveying device described above, articles are supplied simultaneously to a plurality of article holding members when the article holding members are stopped on the first side of the parallel sections and are successively discharged from the article holding members that are moving continuously on the second side of the parallel sections; or articles are continuously supplied to the article holding members that are moving continuously on the second side of the parallel sections and are simultaneously discharged from a plurality of the article holding members when the article holding members are stopped on the first side of the parallel sections.